The compound of formula (I) below, the chemical name of which is 6β,7β;15β,16β-dimethylene -3-oxo-17α-pregn-4-ene-21,17-carbolactone, is commonly indicated by the name drospirenone:

Drospirenone is a synthetic steroid with progestogenic, antimineralocorticoid and antiandrogenic action; thanks to these characteristics, it has been used for some time in the preparation of pharmaceutical compositions with contraceptive action for oral administration.
Various processes for the preparation of drospirenone are known in literature.
The process described in European patent EP 075189 B1 obtains the end product drospirenone by hot oxidation of 17α-(3-hydroxypropyl)-6β,7β;15β,16β-dimethylene -5β-androstane-3β,5,17β-triol with the mixture pyridine/water/chromic anhydride. This step constitutes a substantial drawback of the process: indeed, chromic anhydride, like all Cr(VI) compounds, is a proven carcinogen, the use of which is subject to legislative restrictions such that the precautions required during its use and disposal make it virtually unusable.
Another process for the preparation of drospirenone is described in European patent EP 918791 B8; in the process of this document the drospirenone is obtained, again starting from 17α-(3-hydroxypropyl)-6β,7β;15β,16β-dimethylene-5β-androstane -3β,5,17β-triol, in two distinct phases and employing an oxidant such as for example potassium bromate in the presence of ruthenium salts as catalysts, which necessarily must then be completely eliminated from the product.
European patent EP 1828222 B1 describes a further process, wherein the oxidation step is accomplished by using calcium hypochlorite as oxidant in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl radical or a derivative thereof as a catalyst; in the process of this patent the oxidant is added in portions until completion of the reaction. This process overcomes the disadvantages of the prior art since the calcium hypochlorite is not a carcinogenic reagent, nor is 2,2,6,6-tetramethylpiperidine-1-oxyl radical a metal catalyst that imposes a purification of the end product; however, the need for subsequent additions of reagent and the analytical controls in the course of reaction, however simple, are a hindrance to a standardized production that must proceed continuously or nearly so. Consequently, the method of this patent too has process drawbacks from the point of view of an industrial production.
There is therefore still a need to have a simple process that allows the drawbacks of the prior art to be overcome.